Rotary actuators



Jan. 29, 1963 G. H. LELAND ErAL 3,075,395

ROTARY ACTUATORS Filed Sept. 2l, 1959 INVENTORS JIE. 4

United 3,075,395 ROTARY ACTUATORS Gerald H. Leland, Dayton, Ohio, and Oliver F. Davis, deceased, late of Dayton, Ohio, by Mary A. Davis, executrix, Dayton, Ohio, assignors to Ledex, inc., a

corporation of Ohio Filed Sept. 21, 1959, Ser. No. 841,053 2 Claims. (Cl. 74E-89) This invention relates to rotary actuators and more particularly to a fluid powered device for imparting reciprocatory rotary motion to an output shaft, however the invention is not necessarily so limited.

The present application constitutes a continuationin part of the copending application Serial No. 726,942, filed April 7, 1958, and now abandoned, by Gerald H. Leland and Oliver F. Davis for a Rotary Actuator. Fthis cepending application discloses a rotary actuator which is powered by lluid under pressure and which is characterized by a rotary output stroke which is large in relation to the linear fluid displacement in the actuator. A noteworthy feature of this device is that it is small and compact in View of the power transmitted. The present invention is the result of efforts to improve and simplify the construction of this device, particularly the means with which the propelling fluid is contained within the device.

An object of the present invention is to provide an improved fluid receiving chamber construction for a fluid powered rotary actuator.

Another object of this invention is to provide an i1rproved thrust plate construction for use in iluid powered rotary actuators wherein fluid power is transformed to mechanical power through the medium of a flexible diaphragm operating on the thrust plate, the thrust plate being duofunctional in that it transmits mechanical power while simultaneously providing support for one end of a rotary output shaft. This construction offers the benefit that the rotary output shaft need not project into or through the fluid receiving chamber, thus obviating the need for rotary fluid seals.

Another object of the present invention is to provide an improved thrust bearing design embodying a trapping cage for the bearing elements.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture and the mode of operation, as will become more apparent from the following description.

In the drawing, FGURE l is a longitudinal sectional view of a fluid powered rotary actuator constructed in accordance with this invention.

FIGURE 2 is a sectional view taken substantially along the line 2 2 of FIGURE l and drawn to reduced scale.

FIGURE 3 is a sectional view taken substantially along the line 3-3 of FIGURE 1 and drawn to reduced scale.

FIGURE 4 is a sectional view analogous to that of FIGURE 3 illustrating another position for the rotary actuator.

FIGURE 5 is a longitudinal sectional view of the modilication.

Referring to the drawing in greater detail, the rotary actuator of this invention is enclosed in a generally cylindrical housing which is formed with a circular base l2 press-fitted within a generally cylindrical sleeve i4. Threaded mounting studs lo are press-fitted in the base l2.

Opposite the base l2, the sleeve i4 is closed with a generally circular cap 18 secured to the sleeve 14 by means of bolts 2t). Interposed between the sleeve 14 and the cap iS is a flexible elastomeric diaphragm 22. A fluid seal between the sleeve 14 and the cap i8 is effected by compression of the outer margin of the diaphragm 22 upon tightening of the bolts Ztl. In effect, the diaphragm 22 divides the interior of the housing lo into two charnbers. One chamber adjacent the cap 18 serves as a iluid receiving chamber and communication thereto is afforded by an internally threaded port 24 in the cap 18. The other chamber, which is opposite the cap 18, houses a mechanism for converting axial movement of the diaphragm to rotary movement of an output shaft 26.

The output shaft 26 is supported for rotation at the geometric axis for the housing lil by means of a sleeve bearing 23 press-titled in the base 12. The inner end of the shaft 26 is rotatably received by a socket Sil integral with a generally circular thrust plate 32 positioned adjacent the diaphragm 22. For simplicity of manufacture, the thrust plate 32 and the bearing 28 are formed of a suitable plastic material, such as sintered nylon, which has a low coeilicient of friction in contact with metallic surfaces. It is to be understood, of course, that other plastics may be used and that these parts may also be fabricated from metals. The thrust plate snugly lits the wall of the sleeve 14 so as to contain the diaphragm.

Axial movement of the thrust plate 32 is transmitted to a rotary conversion mechanism, to be described later, by means of a thrust bearing formed with ball elements 34. interposed between the ball elements 34 and the adjacent surface of the thrust plate 32 is an annular reenforcing ring 36 which distributes the contact pressure with the ball elements 34 over a large area Or the thrust plate. The ball elements 34 bear against a metallic thrust receiving plate 3S and are secured adjacent this plate by means of a caging member 4l?. This caging member is provided with suitable apertures 4l through which the ball elements 3d project partially, the diameter of these apertures being less than the diameter of the ball elements 34. This caging member is secured with rotational freedom to the thrust receiving plate 33 with `fingers 42 struck from the periphery thereof so as to hook around outwardly projecting shoulders 44 provided in the periphery of the thrust receiving plate 38. The length of these fingers 42 is such that the ball elements 34 cannot escape their apertures 4l and hence are trapped between the caging member 4d and the thrust receiving plate 38. The lingers 42 are long enough, however, that there is some play in the caging member 4d, the construction being such that the trapping action of the caging member does not interfere with the normal function of the ball elements 34.

The thrust receiving plate 3S is maintained in intimate contact with a companion plate `46 by means of a central keeper 43 Surrounding the shaft 26. This keeper has outwardly projecting shoulders Se and 52 which retain the plates 3d and 4o in fixed relation. The plate 46 is one plate of a rotary conversion mechanism which includes a coacting annular plate 54 and intermediate ball elements 58. The coacting plate 54 is secured iixedly to the base l2 by means of studs 56.

With particular reference to FIGURES 3 and 4, it will be observed that the coacting plates 46 and 54 are provided with oppositely inclined recesses 60 and 62 respectively. In the preferred design, each plate has three such recesses spaced degrees apart, the recesses following an arcuate path concentric to the aXis of rotation of the shaft 26. One ball element 58 is interposed between each pair of opposing recesses 60 and 62. When the coactinig plates 46 and S4 are aligned as in FIGURE 4, so that the ball elements 58 are in the shallow ends of the opposing recesses, an axial thrust driving the plates one toward the other will urge the ball elements to move to the deep ends of the recesses thereby urging relative rotation of the plates 46 and 54. The plate 54 bein anchored to the base l2, it is the plate 46 which is urged to rotate.

The rotary torque on the plate 46 is transmitted to the shaft 26 by means of a spline formed with generally rectangular key inserts 66. With reference to FIGURE 2, these key inserts 66 are seated in notches d4 provided in the shaft 26, each of the inserts 65 having a width which exceeds slightly the diameter of the shaft 26. To accommodate the key inserts 6d, the keeper 48 is provided with a rectangular central aperture o@ the width of whi corresponds to the width of the key inserts, and the height of which corresponds to the distance between the outer surfaces of the key inserts. Through this construction, the key inserts cooperate to couple the keeper 48 non-rotatably to the shaft 26 and serve as bearings for sliding axial movement of the keeper. For this purpose, the key inserts are fabricated from a material which has a low coefficient of .friction in contact with the metal of the keeper. This material may be sintered nylon, for example. To insure eiiicient torque transmission between the plate 46 and the keeper 4S, it may be desirable to weld the plate 4o to the keeper 43. However, in many applications, it sufces .if the plates 38 and 46 are compressed snugly between the shoulders 50 and S2 of the keeper.

With reference to FGURE l, it will be observed that the key inserts o5 project outwardly of the shaft 26 beyond the diameter of the adjacent bearing 28. To secure the shaft 26 against axial movement relative to the housing 10, a retaining ring 7i? is seated in a suitable receiving groove 72 in the shaft 2d adjacent the outer Wall of the base 12. The retaining ring '7d in cooperation with the key inserts 66 secure the shaft 26 against axial movement.

In rotary actuators of this type it is found preferable to preload the ball elements 53 in the rotary conversion mechanism. To accomplish this, a coil spring 74 is interposed between the keeper 48 and the thrust plate 3-2. This spring 74 functions to collapse the iiuid receiving chamber when not under pressure while simultaneously maintainingl a slight bias on the rotary conversion mechamsm.

In operation, the rotary actuator of FIGURE l is conneet-ed to any suitable biasing mechanism, not shown, Which will bias the shaft 26 rotatably so as to urge the plate 46 to the position illustrated in FIGURE 4. Tris sets the rotary conversion mechanism so that an axial thrust delivered by the diaphragm 22 will produce rotary motion of the shaft 26. The biasing mechanism may comprise a coil spring, as one example, or the biasing force may exist inherently in mechanism which is to be operated by the rotary actuator.

The modication illustrated in FIGURE 5 is equipped with its own biasing mechanism, This modified rotary actuator is assembled within the housing 85B formed of a circular base 82 press-fitted into a generally cylindrical sleeve 34. Suitable threaded mounting studs S3 are provided in the base 82.

Opposite the base 82, the sleeve 34- is closed by a cap 86 secured with bolts 88. The outer margin of a partitioning diaphragm 91B is clamped between the cap d6 and the sleeve 841. Access tothe left of the diaphragm 90 as viewed in FGURE 5 is afforded by means of an internally threaded port 92 formed in the cap S6.

Axial thrust of the diaphragm 90 resulting from iiuid pressure transmitted through the port 92 is delivered to a thrust plate 94 adjacent the diaphragm. Axial movement of the thrust plate 94 is utilized to rotate a shaft 100 which is supported for rotation at the geometric axis of the housing d@ by means of a sleeve bearing i102 press-fitted in the base 82 and by means of a socket `104 located in the thrust plate 94. As is the case with the preferred embodiment, it is found advantageous to construct the bearing 102 and the thrust plate 94 from a plastic material such -as sintered nylon; however, it is recognized that other materials may be used satisfactorily.

A rotational torque is obtained with coacting plates `166 and 168 separated by ball elements 119. The construction of these members substantially duplicates the construction of the coacting plates 46 and 54 of the preferred embodiment. The plate 108 is secured iixedly to the base 82 by means of screws 112. The plate 106 is lixedly secured to a central hub 114 which is mounted for sliding axial movement on the shaft 1GO. Axial thrust of the diaphragm is transmitted to the plate 1de by means of ball elements 116 forming a thrust bearing between the thrust plate 94 and a thrust receiving spacer plate 118 mounted on the hub 114 adjacent the plate 166. A reenforcing plate 98 backing up the thrust plate 94 assists in distributing the thrust load over the thrust plate. A shim 9d interposed between the reenforcing plate 9S and the diaphragm 90 functions to prevent extrusion of the diaphragm around the thrust plate 94. For this purpose the shim 96 is dimensioned to tit snugly within the sleeve 84.

As with the preferred embodiment, transmission of rotational torque to the shaft 16d is facilitated through the use of key inserts 120 fitted in suitable notches 122 in diametrically disposed positions in the shaft 10i). Complementary to the key inserts 120, the hub 114 has a rectangular central aperture.

An annular retaining ring 124 seated within a suitable groove in the shaft 166 cooperates with the key inserts 12@ and the bearing l192 to secure the shaft 11N) against axial movement.

A bias effective to set the plates 166 and 108 to the correct position for delivering a rotational torque to the shaft 10d is obtained by means of a coil spring 126 secured at its inner end in a notch 128 in the shaft 100 and secured at its outer end to a plate 130. This plate is anchored to the outside surface of the base 82 by means of nuts 32 threaded o-nto the mounting studs 83.

ln operation, uid under pressure is permitted to ow through the port 92 to the left side of the diaphragm as viewed in FIGURE 5. The axial thrust upon the diaphragm is transmitted to the plate 166 by lmeans of the bearing elements 116. ln response to this axial thrust, the ball elements 11d induce the plate 106 to rotate relative to the plate 168 `thus rotating the shaft 160i. As the shaft 10i? rotates, the ball elements 1161 roll to the deep ends of the opposing recesses in the plates 1% and 108 permitting the thrust plate 94 to move axially to the right as viewed in FiGURE 5. The rotary movement of the shaft 1de also tightens the spring 126. Upon subsequent reduction of fluid pressure, the spring 126 rotates the shaft 19@ in reverse resetting the rotary conversion mechanism and expelling fluid from the receiving chamber located between the diaphragm 90 and the cap 86.

It will be observed that throughout the operation of the rotary actuator the thrust bearing elements 116 are under compression either by force of the uid pressure or by force of the spring 126. This being the case, it is not necessary to cage the thrust bearing elements. However, these elements are retained in a circular configuration with an annular groove 134 disposed in the spacer plate 118.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrange-ment of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the `appended claims.

The invention having been thus described, the following is claimed:

l. In a duid powered actuator `device lfor imparting rotary movement to a shaft, a housing, a flexible diaphragm partitioning said housing into two chambers, means providing a fluid inlet to one of said chambers, a thrust plate positioned for slidingmovernent in the other chamber adjacent said diaphragm, said thrust plate having a periphery intertting the periphery of said other chamber so as to contain said diaphragm, a shaft passing centrally through said other chamber normal to said diaphragm and having one end supported for rotation in said thrust plate, a pair of adjacent annular plates encircling said shaft in said other chamber between said thrust plate and the opposite wall of said housing, the annular plate nearest said thrust plate having freedom for axial movement on said shaft, said plates having opposing inclined arcuate surfaces, a roller element interposed between said plates and coacting with their opposing surfaces to impart relative rotation thereto upon movement of said axially movable plate toward the other plate, means securing said axially movable plate against rotation relative to said shaft and means securing the other annular plate against rotation relative to said housing, and means providing a thrust bearing between said thrust plate and said nearest annular plate whereby rotation of the latter is not transmitted to the former.

2. The device according to claim 1 including yielding means operating between said thrust plate and the nearest annular plate to preload the roller element between the annular plates.

References Cited in the le of this patent UNITED STATES PATENTS Ketchum June 14, Rozner July 9, Hubner Dec. 23, Fitch Jan. 3, Reynolds Sept. 30, Baker Feb. 19, Hall Apr. 1, Kendig Apr. 21, Parisoe et al May 26, Adams May 17, Siravo June 28, Miller et al Mar. 14,

FOREIGN PATENTS Germany July 12, 

1. IN A FLUID POWERED ACTUATOR DEVICE FOR IMPARTING ROTARY MOVEMENT TO A SHAFT, A HOUSING, A FLEXIBLE DIAPHRAGM PARTITIONING SAID HOUSING INTO TWO CHAMBERS, MEANS PROVIDING A FLUID INLET TO ONE OF SAID CHAMBERS, A THRUST PLATE POSITIONED FOR SLIDING MOVEMENT IN THE OTHER CHAMBER ADJACENT SAID DIAPHRAGM, SAID THRUST PLATE HAVING A PERIPHERY INTERFITTING THE PERIPHERY OF SAID OTHER CHAMBER SO AS TO CONTAIN SAID DIAPHRAGM, A SHAFT PASSING CENTRALLY THROUGH SAID OTHER CHAMBER NORMAL TO SAID DIAPHRAGM AND HAVING ONE END SUPPORTED FOR ROTATION IN SAID THRUST PLATE, A PAIR OF ADJACENT ANNULAR PLATES ENCIRCLING SAID SHAFT IN SAID OTHER CHAMBER BETWEEN SAID THRUST PLATE AND THE OPPOSITE WALL OF SAID HOUSING, THE ANNULAR PLATE NEAREST SAID THRUST PLATE HAVING FREEDOM FOR AXIAL MOVEMENT ON SAID SHAFT, SAID PLATES HAVING OPPOSING INCLINED ARCUATE SURFACES, A ROLLER ELEMENT INTERPOSED BETWEEN SAID PLATES AND COACTING WITH THEIR OPPOSING SURFACES TO IMPART RELATIVE ROTATION THERETO UPON MOVEMENT OF SAID AXIALLY MOVABLE PLATE TOWARD THE OTHER PLATE, MEANS SECURING SAID AXIALLY MOVABLE PLATE AGAINST ROTATION RELATIVE TO SAID SHAFT AND MEANS SECURING THE OTHER ANNULAR PLATE AGAINST ROTATION RELATIVE TO SAID HOUSING, AND MEANS PROVIDING A THRUST BEARING BETWEEN SAID THRUST PLATE AND SAID NEAREST ANNULAR PLATE WHEREBY ROTATION OF THE LATTER IS NOT TRANSMITTED TO THE FORMER. 